/*
 * Copyright (C) 2006 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef __WCDB_CURSOR_WINDOW_H__
#define __WCDB_CURSOR_WINDOW_H__

#include <stddef.h>
#include <stdint.h>
#include <string>

#include "Errors.h"
#include "Logger.h"

#if 1

#define IF_LOG_WINDOW() if (false)
#define LOG_WINDOW(...)

#else

#define IF_LOG_WINDOW() IF_ALOG(LOG_DEBUG, "WCDB.CursorWindow")
#define LOG_WINDOW(...) LOGD("WCDB.CursorWindow", __VA_ARGS__)

#endif

namespace wcdb {

/**
 * This class stores a set of rows from a database in a buffer. The begining of the
 * window has first chunk of RowSlots, which are offsets to the row directory, followed by
 * an offset to the next chunk in a linked-list of additional chunk of RowSlots in case
 * the pre-allocated chunk isn't big enough to refer to all rows. Each row directory has a
 * FieldSlot per column, which has the size, offset, and type of the data for that field.
 * Note that the data types come from sqlite3.h.
 *
 * Strings are stored in UTF-8.
**/
class CursorWindow {
    CursorWindow(void *data, size_t size);

public:
    /* Field types. */
    enum {
        FIELD_TYPE_NULL = 0,
        FIELD_TYPE_INTEGER = 1,
        FIELD_TYPE_FLOAT = 2,
        FIELD_TYPE_STRING = 3,
        FIELD_TYPE_BLOB = 4,
    };

    struct RowSlot {
        uint32_t offset;
    };

    /* Opaque type that describes a field slot. */
    struct FieldSlot {
    private:
        int32_t type;
        union {
            double d;
            int64_t l;
            struct {
                uint32_t offset;
                uint32_t size;
            } buffer;
        } data;

        friend class CursorWindow;
    } __attribute((packed));

    ~CursorWindow();

    static status_t create(size_t size, CursorWindow **outCursorWindow);

    inline size_t size() { return mSize; }
    inline size_t freeSpace() { return mSize - mHeader->freeOffset; }
    inline uint32_t getNumRows() { return mHeader->numRows; }
    inline uint32_t getNumColumns() { return mHeader->numColumns; }

    status_t clear();
    status_t setNumColumns(uint32_t numColumns);

    /**
         * Allocate a row slot and its directory.
         * The row is initialized will null entries for each field.
         */
    status_t allocRow(RowSlot **outSlot);
    status_t freeLastRow();

    RowSlot *getRowSlot(uint32_t row);

    status_t
    putBlob(RowSlot *row, uint32_t column, const void *value, size_t size);
    inline status_t
    putBlob(uint32_t row, uint32_t column, const void *value, size_t size)
    {
        return putBlob(getRowSlot(row), column, value, size);
    }

    status_t putString(RowSlot *row,
                       uint32_t column,
                       const char *value,
                       size_t sizeIncludingNull);
    inline status_t putString(uint32_t row,
                              uint32_t column,
                              const char *value,
                              size_t sizeIncludingNull)
    {
        return putString(getRowSlot(row), column, value, sizeIncludingNull);
    }

    status_t putLong(RowSlot *row, uint32_t column, int64_t value);
    inline status_t putLong(uint32_t row, uint32_t column, int64_t value)
    {
        return putLong(getRowSlot(row), column, value);
    }

    status_t putDouble(RowSlot *row, uint32_t column, double value);
    inline status_t putDouble(uint32_t row, uint32_t column, double value)
    {
        return putDouble(getRowSlot(row), column, value);
    }

    status_t putNull(RowSlot *row, uint32_t column);
    inline status_t putNull(uint32_t row, uint32_t column)
    {
        return putNull(getRowSlot(row), column);
    }

    /**
    * Gets the field slot at the specified row and column.
    * Returns null if the requested row or column is not in the window.
    */
    FieldSlot *getFieldSlot(RowSlot *rowSlot, uint32_t column);
    inline FieldSlot *getFieldSlot(uint32_t row, uint32_t column)
    {
        return getFieldSlot(getRowSlot(row), column);
    }

    inline int32_t getFieldSlotType(FieldSlot *fieldSlot)
    {
        return fieldSlot->type;
    }

    inline int64_t getFieldSlotValueLong(FieldSlot *fieldSlot)
    {
        return fieldSlot->data.l;
    }

    inline double getFieldSlotValueDouble(FieldSlot *fieldSlot)
    {
        return fieldSlot->data.d;
    }

    inline const char *getFieldSlotValueString(FieldSlot *fieldSlot,
                                               size_t *outSizeIncludingNull)
    {
        *outSizeIncludingNull = fieldSlot->data.buffer.size;
        return static_cast<char *>(offsetToPtr(fieldSlot->data.buffer.offset));
    }

    inline const void *getFieldSlotValueBlob(FieldSlot *fieldSlot,
                                             size_t *outSize)
    {
        *outSize = fieldSlot->data.buffer.size;
        return offsetToPtr(fieldSlot->data.buffer.offset);
    }

private:
    static const size_t ROW_SLOT_CHUNK_NUM_ROWS = 1023;

    struct Header {
        // Offset of the lowest unused byte in the window.
        uint32_t freeOffset;

        // Offset of the first row slot chunk.
        uint32_t firstChunkOffset;

        uint32_t numRows;
        uint32_t numColumns;
    };

    struct RowSlotChunk {
        uint32_t nextChunkOffset;
        RowSlot slots[ROW_SLOT_CHUNK_NUM_ROWS];
    };

    void *mData;
    size_t mSize;
    Header *mHeader;

    inline void *offsetToPtr(uint32_t offset)
    {
        return static_cast<uint8_t *>(mData) + offset;
    }

    inline uint32_t offsetFromPtr(void *ptr)
    {
        return static_cast<uint8_t *>(ptr) - static_cast<uint8_t *>(mData);
    }

    /**
         * Allocate a portion of the window. Returns the offset
         * of the allocation, or 0 if there isn't enough space.
         * If aligned is true, the allocation gets 4 byte alignment.
         */
    uint32_t alloc(size_t size, bool aligned = false);

    RowSlot *allocRowSlot();

    status_t putBlobOrString(RowSlot *row,
                             uint32_t column,
                             const void *value,
                             size_t size,
                             int32_t type);
};

} // namespace wcdb

#endif
